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August 26, 2016 HWA Project No. 2016-P101-21 BHC Consultants, LLC 1601 Fifth Avenue, Suite 500 Seattle, Washington 98101 Attention: Jim Gross, P.E. Subject: Geotechnical Engineering Services Snohomish River Overflow Structure R4 Everett,Washington Dear Jim: As requested, HWA GeoSciences Inc. (HWA) is pleased to present this scope of work to provide geotechnical engineering services for the design of modifications associated with the Snohomish River Overflow Structure R4 in Everett, Washington. PROJECT UNDERSTANDING It is our understanding that the City of Everett's (City) Snohomish River Overflow 4 (SR04) currently experiences more than the Department of Ecology's allowable average of one CSO per year. To reduce CSO occurrences, modifications to the R4 structure are proposed. R4 currently consists of a manhole with existing 42-inch and 30-inch inlet pipes, a 48-inch primary discharge pipe,and a leaping weir connecting to a 30-inch overflow pipe. Proposed modifications to the R4 system would be to replace this structure with a new vault that includes an inlet chamber for the 42-inch pipe, a primary 48-inch discharge pipe, and an adjustable flat plate style weir that discharges to the 30-inch overflow pipe. These modifications would result in the construction of four manholes that extend to depths ranging from 23 to 25 feet below ground surface. Additionally, a Weir structure would be constructed that would extend to approximately 25 feet below ground surface. Installation of these structures and the associated piping will require completion of deep excavation that will require vertical shoring. Several of the proposed structures will be located within WSDOT right of way. To complete the geotechnical portions of this work,HWA proposes the following scope of work. GEOTECHNICAL ENGINEERINGS SERVICES SCOPE Project Management This work will include the following subtasks. • Geotechnical Project Management: HWA will provide task management for the geotechnical aspects of the project. This will include preparing monthly invoices and